Abstract
A polycrystalline silicon-boron (Si-B) layer with a thickness of 180 nm was grown on recrystallized amorphous silicon in an ultrahigh vacuum chemical vapor deposition (UHV/CVD) system using pure SiH 4 and B 2 H 6 (1% in H 2 ). The growth temperature was as low as 550°C. Auger electron spectroscopy and secondary ion mass spectroscopy showed that the boron concentration is extraordinarily high (2×10 22 cm -3 ). From the analysis of transmission electron diffraction patterns, the phase of silicon hexaboride (SiB 6 ) was found to be present in the as-deposited Si-B layer. After thermal annealing, most of the boron atoms in the Si-B layer were found to be immobile. The presence of SiB 6 in the Si-B layer may lead to the reduction of boron diffusivity in the Si-B layer during thermal annealing.